This invention relates to a pipe seal assembly for use in on-site waste disposal systems, such as in a septic system having a poured concrete septic tank, drop box or distribution box.
These tanks and boxes are box-shape structures constructed of concrete and have plural openings for the receipt of outlet and inlet pipes. Depending upon the particular arrangement, a number of pipes may be employed at one or more levels and the maximum number of openings are usually provided in the box. In certain prior constructions, the openings were simply holes formed in the box's side walls. More recently, these openings may be initially closed by seal assemblies and those openings for which pipes are intended have a removable portion of the seal assembly removed. The remaining part of the seal assembly is adapted to provide a water-tight seal for the inserted pipe.
A problem has arisen with respect to seal assemblies where flowing concrete has interfered with the seal to be developed with the pipe. Additionally, another disadvantage of known seals which mount on form mandrels is that they must be manually held in place while the form is open before casting, until such time as the form is closed; otherwise the seals simply fall off the mandrels.
The problems are avoided by the instant invention. More particularly, the instant invention provides for a releasably retained knock-out plug positioned adjacent the end of the seal assembly and, when the seal assembly is cast in place in the concrete box, the plug is located near the interior wall of the box. A specially configured mandrel supported on the form wall operates to releasably hold the seal and plug in place during casting of the box. The mandrel can include gripper structure for frictionally holding the seal in place, or can include undercut structure for gripping the seal. Additionally, the present seals' cylindrical body portion can be so dimensioned that the back of one seal can be placed over the front of another seal, such that a connected series of such seals mounted on only one mandrel can be used to seal a pipe through a thick poured concrete basement wall, for example.
Other objects and advantages of the invention may be seen in the details of the ensuing specification.